Combustion engine



Sept. 13, 1949. F, PRIETQ 2,481,872

COMBUSTION ENGINE Filed Sept. 19, 1947 Patented Sept. 13, 1949 ED STATES FATE NT OF P ICE- 2;4s1,sva coMBUsrrroN Enema Fernando/ G; Prieto, Lesen zeleslcanr.

Application. September 19, 1947,, Serial No; 7'7 5,08 1;

(01; ne -tel 4 Claims.

The present invention relates to an improved combustion engine and deals more specifically with-a two-stroke cycle engine and with a novel manner of applying the power of said engine.

The objects of the present invention are: to provide an improved" engine that has ahigh power output; to provide an engine of the character indicatedwhichhas an efiicient weightper power output ratio and which is economical to both manufacture and operate; to provide an improved" internal combustion engine which efflcientlyv conserves: fuel; to provide an improved combustion engine in which emcient scavenging of the cylinders thereof is efficiently effected.

The foregoing. and other objects, features and advantages ofthe invention willbe more clearly realized" from the following detailed description ofthe structure illustratedin the accompanying drawing which shows, by way of example an engine embodying the present invention, and in which;

Fig. 1 is a' longitudinal sectional view of an engine embodying, featuresof the invention.

Fig. 2 is a longitudinal sectionalview thereof taken at right angles to the plane'of Fig. 1.

Fig. 3 is a longitudinal sectional viewv of a; modification ofthe engine.-

Referring to the drawing in great detail, the engine shown comprises acylinder 1, which-is closed at 'its ends it and 9--andisprovided w-ith a 1' working piston-Wand a-free piston II. The-engine further-includesaerankshaft l2 connected to the working piston H] by means of a piston rod [3 and a crank rod I4. The working piston i0 is provided with a longitudinal passage 15 controlled by a flap valve 16 which opens inwardly to allow a fuel charge to pass from the outer face 20 to the inner face 2| of said working piston. Sliding bolts Illa connect the pistons for both unitary and relative movement. Said cylinder is also provided with exhaust valves IQ for the gases of combustion of the engine, said valves being operated by conventional means (not shown) to alternately open in synchrony with the operation of the engine.

It will be seen that bolts l0a each have a head 22 on each end, that said heads are longitudinally movable in passages 23 extending through each piston l0 and H, and that each passage 23 is provided with end abutments 24 limiting the movement of the heads and providing the slidable connection indicated.

The engine structure also includes a tube [1 arranged longitudinally alongside of the cylinder, controlled by flap valves Ila, one at each end 2i of said tube, to allow the fuel charge to ee-s rens the'space lb; atonee'ndof the cylinder; into-the space" To. at th-eother end; V p

The space ibis-provided witha'f-uellin'e" l8 for admitting a fuel charge to the cylinder bydisplacing a back pressurevalve' I8a'ir'rsaid line! The engine above? set forth may be used in variousways; Herein; its operation will be de' scribed with rennon to avehicle which ii? pro pels. In such an'instan'ce; the engine" is generally disposed in the pl'arieor line of movement of the vehi'cle' in whichitis embodied,

The operationof the present structure is as follows:

fiuring the ill-stroke of the piston HF inadir-ection towardcylinder? end 8 a fuel charge" is drawn into 'the' space- 16 and said pistoncoming into contact With the nee piston; H; compress it fuelchargewhich had previously been displaced into the'co'mbustionchamberformed in the s-pace la between-the free piston H and "th'ec'ylind'e'r head 8. The latter compress-ed fuel charge' is ignited by esuitable spark or other firing means (not show-n) 'rhe resulnngg'as expansion while exerting a pressure on=tl'ie-cylinder"headf 8- causes the work ing stroke to begin by" propelling both pistons I 0 and" l 3 outwardly toward th'e' cylinder end- The fie piston H receives its moving force dir'ectlyfiorflthe expanding gases, and the piston I0 receives its thrust by direct contact was thefreeiston' I I; During? said workingsti'okiethefuel cliarge in' the space'lb will; in turn,- be compressed.said pressure-automatically closing the fuel valve [8a. This pressure becomes a force that, through passage l5, will open the valve "5 of the piston l0 so that the fuel charge will pass through the passage I5 into a space 10 between the two pistons Ill and H. The free piston ll, instead of continuing to follow the outward movement of the working piston I0, is gradually slowed up by the counteracting force of the compressed charge in chamber 10 until it reverses its movement. Such reversal of movement is caused by both the incoming fuel charge and the gradual loss of force of the fully expanded gases of combustion in chamber 1a. During the next instroke of the piston I0 a new fuel charge is drawn into the space lb and the combustion chamber 1a is simultaneously exhausted while the piston l0 compresses the fuel charge in the space 10, this compressed fuel charge acting in turn on the free piston II to propel said free piston against the cylinder head 8. The space To now becomes the combustion chamber. Upon ignition of this fuel charge, the new working-stroke be gins. Again, the expanding gases of combustion exert a pressure on the cylinder head 8, through the free piston II which is in contact with said cylinder head. The piston I during a part of its moving outwardly pulls the free piston II by means of the bolts Ma and then the fuel charge in the space lb pass through the tube l1 into the space 1a which becomes again the combustion chamber, and the above described operation is repeated.

It will be evident that, upon each power stroke of the piston 10, the crankshaft 12 receives power from the engine. Simultaneously, the cylinder end 8 is subjected to either direct pressure of expanding gases in combustion chamber la or to the pressure in chamber 10 (as applied through piston II) to produce a thrust that may be employed, as for moving a vehicle. This thrust is a reactive force of positive nature, and, since it is applied directly, without any transmission, while the force on the piston is absorbed in the crankshaft, the former is more effective than the latter to move a vehicle especially if the crankshaft has little or no resistance to overcome.

The engine shown in Fig. 3 is similar to that above described with the exception that the working piston I0 is formed with an enlarged end 25 and the cylinder commensurately enlarged at the fuel intake end. Thus a large fuel charge can be taken into chamber lb with a resultant higher compression ratio for the engine.

Only the essentials of my engine structure have been disclosed and it is obvious that skilled persons can readily incorporate such attending instrumentalities that may be needed to complete the structure. Further, many changes may be made in the construction and arrangement of the parts without departing from the spirit and scope of the invention as claimed. I, therefore, desire to reserve to myself such variations that fall Within the scope of the appended claims.

I claim:

1. A two-stroke cycle internal combustion engine comprising, at least one cylinder having opposed ends, one working piston in each cylinder,

a free piston freely movable between said working piston and one end of said cylinder to form a combustion chamber between itself and said cylinder end and between itself and said working piston alternately, a crankshaft, means connecting the working piston to the crankshaft, a fuelconducting passage outside the cylinder and communicating with the cylinder adjacent its opposed ends, an automatic valve in said passage controlling the transferring of the fuel charge from one end of the cylinder to the other, and a valve-controlled passage in the working piston for transferring the fuel charge from one end of the cylinder to the combustion chamber formed between said working piston and said free piston.

2. A two-stroke cycle internal combustion engine comprising, a cylinder having opposed ends, a piston in said cylinder and having a passage therethrough, a valve in said passage controlling flow in one direction only, a crankshaft, means extending in a direction opposite to that in which said valve opens and through one end of the cylinder operatively connecting said piston and crankshaft, a free piston in that end of the cylinder that is opposite to the latter means, means connecting the pistons for both relative movement and movement together in the same direction, and a valve-controlled passage con necting the opposite ends of the cylinder, said valve in the piston controlling flow from one end of the cylinder to between the pistons and the valve-controlled passage, alternately controlling flow between the ends of the cylinder during each cycle of the engine.

3. The engine as set forth in claim 2 in which the means connecting the pistons comprises at least one elongated member having a head on each end and movable in passages in said pistons having opposed abutments engaging said heads to limit the relative movement of the pistons.

4. The engine as set forth in claim 2 in which the piston having the valve-controlled passage is formed with an enlarged end on the end directed toward the crankshaft and in which the cylinder is enlarged to accommodate said enlarged end whereby the volume at said end of the cylinder is larger than the volume at the opposite end.

FERNANDO G. PRIETO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 792,119 Clifton June 13, 1905 928,405 Simon July 20, 1909 1,337,077 Kershaw Apr. 13, 1920 

